1. Field of the Invention
The present invention relates to a vehicle mirror apparatus, and specifically relates to a vehicle mirror apparatus having a mirror surface angle detection device of the type in which a mirror surface angle is detected using a male thread member and a nut member of a tilting device (mirror surface angle adjustment actuator). The present invention eliminates the need to, in such type of mirror surface angle detection device, bias a mover for mirror surface angle detection by means of a spring in order to move the mover following the nut member along the male thread member in such a manner that the mover is rotatable relative to the nut member and is non-rotatable relative to the male thread member.
2. Description of the Related Art
In vehicle mirror apparatuses including a tilting device, a mirror surface angle detection device is installed in, e.g., what is called a memory mirror or what is called a reverse interlock mirror. A memory mirror is a mirror that automatically adjusts a mirror surface angle to a prestored angle. A reverse interlock mirror is a mirror that in association with gear shift operation means of the vehicle being thrown into a reverse position, automatically rotates a mirror surface of a vehicle outside mirror downward by a predetermined amount of angle to enable a driver to view an area around the rear wheel. Japanese Patent Laid-Open No. 10-67281 and Japanese Patent No. 4217187 each describe a conventional mirror surface angle detection device for a vehicle mirror apparatus. The vehicle mirror apparatus described in Japanese Patent Laid-Open No. 10-67281 includes an independent mirror surface angle detection device provided separately from a male thread member and a nut member included in a tilting device. The vehicle mirror apparatus described in Japanese Patent No. 4217187 includes a mirror surface angle detection device using a male thread member and a nut member.
FIG. 12 illustrates a tilting device equipped with the mirror surface angle detection device described in Japanese Patent No. 4217187. In FIG. 12, parts corresponding to respective parts of the later-described embodiment of the present invention are provided with reference numerals that are the same as those of the embodiment. The tilting device is configured as follows. An actuator housing 12 (base member) is fixed to a mirror housing (not illustrated). In the actuator housing 12, a plate pivot 46 (tilting member) is supported so as to be tiltable around a predetermined tilting center (not illustrated). On the plate pivot 46, a mirror (not illustrated) is mounted. At a part of the actuator housing 12 that is off the tilting center, a male thread member 16 with a male thread formed at an outer peripheral surface thereof is provided in a standing manner. A rear end of an adjustment nut 28 (nut member) is rotatably screwed on a free end of the male thread member 16 and covers the free end, and a projecting spherical portion 28a of a front end of the adjustment nut 28 is connected to a recessed spherical portion 53 formed at a part of the plate pivot 46 that is off the tilting center, by ball joint connection. Upon the motor 20 being driven, rotation of the motor 20 is transmitted to the adjustment nut 28 via a worm gear 36 and a wheel worm 24. Consequently, the adjustment nut 28 ascends and descends along the male thread member 16 while rotating, and tilts the plate pivot 46 to adjust a mirror surface angle.
The mirror surface angle detection device is configured as follows. A communication hole 17 is provided in the male thread member 16 along a shaft axis of the male thread member 16. A slide block 90 (mover) is inserted through the communication hole 17 in such a manner that the slide block 90 is movable in an axial direction. The slide block 90 is biased by a coil spring 11 disposed between the actuator housing 12 and the slide block 90 to press the slide block 90 against a surface in a back of the projecting spherical portion 28a of the adjustment nut 28 and thereby make the slide block 90 abut against the surface, whereby the slide block 90 is locked. A hollow of the slide block 90 houses a slide contact 91 (contact member) in such a manner that the slide contact 91 is non-movable relative to the slide block 90 in neither an axial direction nor a shaft rotation direction. The slide contact 91 pinches a print wiring board 94 fixed to the actuator housing 12 so as to stand on the actuator housing 12 and thereby the slide contact 91 is in contact with a resistor printed on a surface of the print wiring board 94. Rotation of the slide block 90 is blocked by the force of pinching the print wiring board 94 by the slide contact 91. Upon the adjustment nut 28 being rotated as a result of the motor 20 being driven and the adjustment nut 28 moving along the male thread member 16, the slide block 90 moves following the adjustment nut 28 in an axial direction of the male thread member 16 without rotation, by means of a pressing force of the coil spring 11. Consequently, a position in the print wiring board 94 that is in contact with the slide contact 91 changes, and the contact position change is detected as a voltage change resulting from a resistance value change, whereby a mirror surface angle is detected.
The mirror surface angle detection device described in Japanese Patent Laid-Open No. 10-67281 requires provision of an independent mirror surface angle detection device separately from a male thread member and a nut member in a tilting device. The mirror surface angle detection device described in Japanese Patent No. 4217187 enables provision of a mirror surface angle detection device using a male thread member and a nut member in a tilting device, but requires the slide block 90 to be biased by the coil spring 11 in order to move the slide block 90 following the adjustment nut 28 along the male thread member 16 in such a manner that the slide block 90 is rotatable relative to the adjustment nut 28 and is non-rotatable relative to the male thread member 16.
The present invention is intended to solve the aforementioned problems of the conventional techniques in a vehicle mirror apparatus having a mirror surface angle detection device of the type in which a mirror surface angle is detected using a male thread member and a nut member in a tilting device. In other words, the present invention is intended to provide a vehicle mirror apparatus having a mirror surface angle detection device that eliminates the need to bias a mover using a spring in order to move the mover following a nut member along a male thread member in such a manner that the mover is rotatable relative to the nut member and is non-rotatable relative to the male thread member.